This invention is related to powder coating compositions and in particular to a polyvinyl chloride containing powder coating composition.
Powder coating compositions are well known in the art and have been used in the place of conventional solvent and water-based paints to coat a variety of different substrates. Polyvinyl chloride powder coatings are broadly used and well known as shown by Richardson U.S. Pat. No. 3,842,027 issued Oct. 15, 1974. These polyvinyl chloride powder coatings are applied by conventional fluid bed or electrostatic spray techniques. However, these polyvinyl chloride powders agglomerate and lose free flow characteristics when exposed to heat and pressure in storage or in application equipment. When this occurs, additional sieving or mixing of the powder is required to achieve uniform application of the powder on substrates.
Another deficiency of the polyvinyl chloride powders is that relatively thin finishes of the powders about 1-2 mils in thickness contain pinholes and make the powder unacceptable as an exterior finish for metals.